PLANETESIMAL HYPOTHESIS

Moulton had different explanation of the origin of the solar system. He and geologist Thomas C. Chamberlin proposed Planetesimal Hypothesis. This theory is based in part on the ideas put forth by one of Kant's contemporaries - the french naturalist Comte Georges Louis Leclerc de Buffon. Buffon suggested that the bits of matter that would become the planets were the result of a collision between the Sun and a Comet. Modern astronomers dismiss the idea that there could ever be a comet large enough to have had such an effect. But the idea became the seed of Chamberlin and Moulton's planetesimal hypothesis.

Instead of a cometary collision, they postulated that the surface of the Sun was disturbed by the gravitational pull of a passing star. The colossal tug tore chunks of gaseous material from the stellar surface. Some of this material was pulled along in the passing star's wake, but some of the dislodged chunks remained in orbit around the Sun. They cooled and solidified into hard masses that Moulton and Chamberlin dubbed Planetesimals. Many of the planetesimals orbiting in the same plane collided and combined to form larger and larger planetesimals. The bigger each planetesimal became, the greater its gravitational pull on surrounding material.